Surgical needles and methods of manufacturing surgical needles are well known in the art. Surgical needles typically consist of a shaft-like member, which may be curved or straight. The member has a distal piercing point and a proximal end for mounting or receiving a suture. Surgical needles are typically classified as either taper-point needles, wherein the diameter of the shaft tapers to a piercing point, or cutting edge needles wherein the needles have various cutting edges along with piercing points to assist in penetrating various types of tissue.
Surgical sutures may be attached or mounted to the proximal ends of surgical needles in various ways. One common way is to have a channel formed into the proximal end of the needle. The channel end typically is die-formed into a needle during the manufacturing process and consists of a cavity. When a surgical suture end or tip is placed into the cavity, the channel end is hit with a die one or more times under pressure forcing the sidewalls closed tightly about the suture tip to prevent the suture from separating from the needle. The process of mounting a suture tip to the proximal end of a needle is known in the art as swaging. Another manner in which a suture may be mounted to a surgical needle is by drilling a hole, commonly referred to in the art as blind hole, into the proximal end of the needle. This can be done using conventional mechanical drilling apparatuses or conventional laser drilling apparatuses. The end or tip of a suture is then inserted into the drilled hole and the section of the proximal end of the needle surrounding the blind hole is swaged in a conventional manner by compressing with various conventional dies. It is also known to mount sutures to surgical needles using conventional adhesives.
Surgical needles are conventionally manufactured from surgical grade alloys, such as surgical grade stainless steel, which are purchased from manufacturers in the form of rod or wire. The rod is drawn into wire and rolled onto a spool. The initial step in the manufacture of surgical needles is to remove the wire from the spool, degrease or clean if required, and then cut the wire into sections known as needle blanks. Each blank will have a length greater than the length of the finished needle, since material will necessarily be removed from the blank during the needle manufacturing process.
A conventional process for manufacturing a taper point needle typically consists of cutting wire into needle blanks and taking each needle blank and subjecting the blank to a series of grinding operations. This is conventionally done in the following manner. The needle blanks are fed into a conventional belt/stone grinding machine where they are given a distal tip. The needles are then transported individually or in bulk to a conventional needle drilling station wherein the needles are drilled using conventional carbide or tool steel drill bits to provide a proximal suture mounting cavity. The needles are then typically degreased and moved in bulk to a conventional belt/stone grinding machine for the finish taper grind and then to a curving machine to produce a conventional curved configuration. The needles are then cleaned, heat treated and may be electrochemically treated to additionally finish the needles. The conventional process is a batch process requiring the handling of the needles in bulk containers to transport them to and from the various work stations. Needles may become damaged or intermingled during such bulk transfers. In addition, the needles must typically be individually mounted in chucks in each machine at each work station. Although this chuck mounting step may in some circumstances be automated, it is typically a time consuming, labor intensive operation.
One conventional method of manufacturing cutting edge needles consists of initially cutting wire into blanks as described above. The distal tips of the needle blanks are then rotary swaged in a rotary swaging machine to produce a conical point having a spud. The spud is next partially cut and the needle blanks are then moved to a belt/stone grinder and mounted into chucks wherein the distal tip of each needle blank is given the final grind to create the necessary shape for bayonet closed die forming. The needle blanks are then moved in bulk or by chuck to a die station where each needle blank is die-formed. The needle blanks are then subjected to a series of grinding operations in a conventional belt/stone grinding machine to produce the cutting edge shape, for example, eight or more separate grinds. The needle blanks must be removed from the chucks and remounted in chucks after and prior to each grinding step, typically by using a walking beam mechanism. The extensive bulk and manual handling required by this process may result in damage to the needles, including the dulling of the points. In addition, the needle machines used in the prior art processes are operator dependent. Each operator tends to set up a machine differently resulting in variability in needle geometry and performance characteristics. Since surgical needles are quality control tested prior to release, the problems associated with the prior art processes tend to result in a financial burden upon the manufacturer in that a significant amount of the needles produced may have to be rejected and destroyed.
The previously described processes are labor intensive and typically utilize low speed, low output equipment. The needles are typically manually handled and transferred in bulk containers between various work stations or machines. In addition, numerous grinding steps are usually required. Often, needles are damaged, including the dulling of needle points, due to the extensive handling and numerous grinding steps which are present in these processes. It is known that grinding operations are by their very nature imprecise resulting in wide variations in the dimensions of the finished needles. This imprecision resultingly yields a significant degree of geometric variability.
Accordingly, what is needed in this art is a process for manufacturing taper point needles which is efficient and substantially minimizes manual handling and also minimizes grinding.